Relief of pain due to uterine cramping/involution after birth

Background

Women may experience differing types of pain and discomfort following birth, including cramping pain (often called after‐birth pain) associated with uterine involution, where the uterus contracts to reduce blood loss and return the uterus to its non‐pregnant size. This is an update of a review first published in 2011.
Objectives

To assess the effectiveness and safety of pharmacological and non‐pharmacological pain relief/analgesia for the relief of after‐birth pains following vaginal birth.
Search methods

For this update, we searched Cochrane Pregnancy and Childbirth’s Trials Register, ClinicalTrials.gov, the WHO International Clinical Trials Registry Platform (ICTRP) (31 October 2019), and reference lists of retrieved studies.
Selection criteria

Randomised controlled trials comparing two different types of analgesia or analgesia versus placebo or analgesia versus no treatment, for the relief of after‐birth pains following vaginal birth. Types of analgesia included pharmacological and non‐pharmacological. Quasi‐randomised trials were not eligible for inclusion.
Data collection and analysis

Two review authors independently assessed trials for inclusion, conducted 'Risk of bias' assessment, extracted data and assessed the certainty of the evidence using the GRADE approach.
Main results

In this update, we include 28 studies (involving 2749 women). The evidence identified in this review comes from middle‐ to high‐income countries. Generally the trials were at low risk of selection bias, performance bias and attrition bias, but some trials were at high risk of bias due to selective reporting and lack of blinding. Our GRADE certainty of evidence assessments ranged from moderate to very low certainty, with downgrading decisions based on study limitations, imprecision, and (for one comparison) indirectness.

Most studies reported our primary outcome of adequate pain relief as reported by the women. No studies reported data relating to neonatal adverse events, duration of hospital stay, or breastfeeding rates. Almost half of the included studies (11/28) excluded breastfeeding women from participating, making the evidence less generalisable to a broader group of women.

Non‐steroidal anti‐inflammatory drugs (NSAIDs) compared to placebo

NSAIDs are probably better than placebo for adequate pain relief as reported by the women (risk ratio (RR) 1.66, 95% confidence interval (CI) 1.45 to 1.91; 11 studies, 946 women; moderate‐certainty evidence). NSAIDs may reduce the need for additional pain relief compared to placebo (RR 0.15, 95% CI 0.07 to 0.33; 4 studies, 375 women; low‐certainty evidence). There may be a similar risk of maternal adverse events (RR 1.05, 95% CI 0.78 to 1.41; 9 studies, 598 women; low‐certainty evidence).

NSAIDs compared to opioids

NSAIDs are probably better than opioids for adequate pain relief as reported by the women (RR 1.33, 95% CI 1.13 to 1.57; 5 studies, 560 women; moderate‐certainty evidence) and may reduce the risk of maternal adverse events (RR 0.62, 95% CI 0.43 to 0.89; 3 studies, 255 women; low‐certainty evidence). NSAIDs may be better than opioids for the need for additional pain relief, but the wide CIs include the possibility that the two classes of drugs are similarly effective or that opioids are better (RR 0.37, 95% CI 0.12 to 1.12; 2 studies, 232 women; low‐certainty evidence).

Opioids compared to placebo

Opioids may be better than placebo for adequate pain relief as reported by the women (RR 1.26, 95% CI 0.99 to 1.61; 5 studies, 299 women; low‐certainty evidence). Opioids may reduce the need for additional pain relief compared to placebo (RR 0.48, 95% CI 0.28 to 0.82; 3 studies, 273 women; low‐certainty evidence). Opioids may increase the risk of maternal adverse events compared with placebo, although the certainty of evidence is low (RR 1.59, 95% CI 0.99 to 2.55; 3 studies, 188 women; low‐certainty evidence).

Paracetamol compared to placebo

Very low‐certainty evidence means we are uncertain if paracetamol is better than placebo for adequate pain relief as reported by the women, the need for additional pain relief, or risk of maternal adverse events (2 studies, 123 women).

Paracetamol compared to NSAIDs

Very low‐certainty evidence means we are uncertain if there are any differences between paracetamol and NSAIDs for adequate pain relief as reported by the women, or the risk of maternal adverse events. No data were reported about the need for additional pain relief comparing paracetamol and NSAIDs (2 studies, 112 women).

NSAIDs compared to herbal analgesia

We are uncertain if there are any differences between NSAIDs and herbal analgesia for adequate pain relief as reported by the women, the need for additional pain relief, or risk of maternal adverse events, because the certainty of evidence is very low (4 studies, 394 women).

Transcutaneous nerve stimulation (TENS) compared to no TENS

Very low‐certainty evidence means we are uncertain if TENS is better than no TENS for adequate pain relief as reported by the women. No other data were reported comparing TENS with no TENS (1 study, 32 women).
Authors' conclusions

NSAIDs may be better than placebo and are probably better than opioids at relieving pain from uterine cramping/involution following vaginal birth. NSAIDs and paracetamol may be as effective as each other, whereas opioids may be more effective than placebo. Due to low‐certainty evidence, we are uncertain about the effectiveness of other forms of pain relief. Future trials should recruit adequate numbers of women and ensure greater generalisability by including breastfeeding women. In addition, further research is required, including a survey of postpartum women to describe appropriately their experience of uterine cramping and involution. We identified nine ongoing studies, which may help to increase the level of certainty of the evidence around pain relief due to uterine cramping in future updates of this review.